diff options
Diffstat (limited to 'crypto/openssh/session.c')
| -rw-r--r-- | crypto/openssh/session.c | 1516 |
1 files changed, 1516 insertions, 0 deletions
diff --git a/crypto/openssh/session.c b/crypto/openssh/session.c new file mode 100644 index 000000000000..53d20c59cf25 --- /dev/null +++ b/crypto/openssh/session.c @@ -0,0 +1,1516 @@ +/* + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + */ +/* + * SSH2 support by Markus Friedl. + * Copyright (c) 2000 Markus Friedl. All rights reserved. + */ + +#include "includes.h" +RCSID("$OpenBSD: session.c,v 1.12 2000/05/03 18:03:07 markus Exp $"); + +#include "xmalloc.h" +#include "ssh.h" +#include "pty.h" +#include "packet.h" +#include "buffer.h" +#include "cipher.h" +#include "mpaux.h" +#include "servconf.h" +#include "uidswap.h" +#include "compat.h" +#include "channels.h" +#include "nchan.h" + +#include "bufaux.h" +#include "ssh2.h" +#include "auth.h" + +/* types */ + +#define TTYSZ 64 +typedef struct Session Session; +struct Session { + int used; + int self; + int extended; + struct passwd *pw; + pid_t pid; + /* tty */ + char *term; + int ptyfd, ttyfd, ptymaster; + int row, col, xpixel, ypixel; + char tty[TTYSZ]; + /* X11 */ + char *display; + int screen; + char *auth_proto; + char *auth_data; + int single_connection; + /* proto 2 */ + int chanid; +}; + +/* func */ + +Session *session_new(void); +void session_set_fds(Session *s, int fdin, int fdout, int fderr); +void session_pty_cleanup(Session *s); +void session_proctitle(Session *s); +void do_exec_pty(Session *s, const char *command, struct passwd * pw); +void do_exec_no_pty(Session *s, const char *command, struct passwd * pw); + +void +do_child(const char *command, struct passwd * pw, const char *term, + const char *display, const char *auth_proto, + const char *auth_data, const char *ttyname); + +/* import */ +extern ServerOptions options; +extern char *__progname; +extern int log_stderr; +extern int debug_flag; + +/* Local Xauthority file. */ +static char *xauthfile; + +/* data */ +#define MAX_SESSIONS 10 +Session sessions[MAX_SESSIONS]; + +/* Flags set in auth-rsa from authorized_keys flags. These are set in auth-rsa.c. */ +int no_port_forwarding_flag = 0; +int no_agent_forwarding_flag = 0; +int no_x11_forwarding_flag = 0; +int no_pty_flag = 0; + +/* RSA authentication "command=" option. */ +char *forced_command = NULL; + +/* RSA authentication "environment=" options. */ +struct envstring *custom_environment = NULL; + +/* + * Remove local Xauthority file. + */ +void +xauthfile_cleanup_proc(void *ignore) +{ + debug("xauthfile_cleanup_proc called"); + + if (xauthfile != NULL) { + char *p; + unlink(xauthfile); + p = strrchr(xauthfile, '/'); + if (p != NULL) { + *p = '\0'; + rmdir(xauthfile); + } + xfree(xauthfile); + xauthfile = NULL; + } +} + +/* + * Function to perform cleanup if we get aborted abnormally (e.g., due to a + * dropped connection). + */ +void +pty_cleanup_proc(void *session) +{ + Session *s=session; + if (s == NULL) + fatal("pty_cleanup_proc: no session"); + debug("pty_cleanup_proc: %s", s->tty); + + if (s->pid != 0) { + /* Record that the user has logged out. */ + record_logout(s->pid, s->tty); + } + + /* Release the pseudo-tty. */ + pty_release(s->tty); +} + +/* + * Prepares for an interactive session. This is called after the user has + * been successfully authenticated. During this message exchange, pseudo + * terminals are allocated, X11, TCP/IP, and authentication agent forwardings + * are requested, etc. + */ +void +do_authenticated(struct passwd * pw) +{ + Session *s; + int type; + int compression_level = 0, enable_compression_after_reply = 0; + int have_pty = 0; + char *command; + int n_bytes; + int plen; + unsigned int proto_len, data_len, dlen; + + /* + * Cancel the alarm we set to limit the time taken for + * authentication. + */ + alarm(0); + + /* + * Inform the channel mechanism that we are the server side and that + * the client may request to connect to any port at all. (The user + * could do it anyway, and we wouldn\'t know what is permitted except + * by the client telling us, so we can equally well trust the client + * not to request anything bogus.) + */ + if (!no_port_forwarding_flag) + channel_permit_all_opens(); + + s = session_new(); + s->pw = pw; + + /* + * We stay in this loop until the client requests to execute a shell + * or a command. + */ + for (;;) { + int success = 0; + + /* Get a packet from the client. */ + type = packet_read(&plen); + + /* Process the packet. */ + switch (type) { + case SSH_CMSG_REQUEST_COMPRESSION: + packet_integrity_check(plen, 4, type); + compression_level = packet_get_int(); + if (compression_level < 1 || compression_level > 9) { + packet_send_debug("Received illegal compression level %d.", + compression_level); + break; + } + /* Enable compression after we have responded with SUCCESS. */ + enable_compression_after_reply = 1; + success = 1; + break; + + case SSH_CMSG_REQUEST_PTY: + if (no_pty_flag) { + debug("Allocating a pty not permitted for this authentication."); + break; + } + if (have_pty) + packet_disconnect("Protocol error: you already have a pty."); + + debug("Allocating pty."); + + /* Allocate a pty and open it. */ + if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, + sizeof(s->tty))) { + error("Failed to allocate pty."); + break; + } + fatal_add_cleanup(pty_cleanup_proc, (void *)s); + pty_setowner(pw, s->tty); + + /* Get TERM from the packet. Note that the value may be of arbitrary length. */ + s->term = packet_get_string(&dlen); + packet_integrity_check(dlen, strlen(s->term), type); + /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */ + /* Remaining bytes */ + n_bytes = plen - (4 + dlen + 4 * 4); + + if (strcmp(s->term, "") == 0) { + xfree(s->term); + s->term = NULL; + } + /* Get window size from the packet. */ + s->row = packet_get_int(); + s->col = packet_get_int(); + s->xpixel = packet_get_int(); + s->ypixel = packet_get_int(); + pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); + + /* Get tty modes from the packet. */ + tty_parse_modes(s->ttyfd, &n_bytes); + packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type); + + session_proctitle(s); + + /* Indicate that we now have a pty. */ + success = 1; + have_pty = 1; + break; + + case SSH_CMSG_X11_REQUEST_FORWARDING: + if (!options.x11_forwarding) { + packet_send_debug("X11 forwarding disabled in server configuration file."); + break; + } +#ifdef XAUTH_PATH + if (no_x11_forwarding_flag) { + packet_send_debug("X11 forwarding not permitted for this authentication."); + break; + } + debug("Received request for X11 forwarding with auth spoofing."); + if (s->display != NULL) + packet_disconnect("Protocol error: X11 display already set."); + + s->auth_proto = packet_get_string(&proto_len); + s->auth_data = packet_get_string(&data_len); + packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type); + + if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER) + s->screen = packet_get_int(); + else + s->screen = 0; + s->display = x11_create_display_inet(s->screen, options.x11_display_offset); + + if (s->display == NULL) + break; + + /* Setup to always have a local .Xauthority. */ + xauthfile = xmalloc(MAXPATHLEN); + strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); + temporarily_use_uid(pw->pw_uid); + if (mkdtemp(xauthfile) == NULL) { + restore_uid(); + error("private X11 dir: mkdtemp %s failed: %s", + xauthfile, strerror(errno)); + xfree(xauthfile); + xauthfile = NULL; + /* XXXX remove listening channels */ + break; + } + strlcat(xauthfile, "/cookies", MAXPATHLEN); + open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600); + restore_uid(); + fatal_add_cleanup(xauthfile_cleanup_proc, NULL); + success = 1; + break; +#else /* XAUTH_PATH */ + packet_send_debug("No xauth program; cannot forward with spoofing."); + break; +#endif /* XAUTH_PATH */ + + case SSH_CMSG_AGENT_REQUEST_FORWARDING: + if (no_agent_forwarding_flag || compat13) { + debug("Authentication agent forwarding not permitted for this authentication."); + break; + } + debug("Received authentication agent forwarding request."); + auth_input_request_forwarding(pw); + success = 1; + break; + + case SSH_CMSG_PORT_FORWARD_REQUEST: + if (no_port_forwarding_flag) { + debug("Port forwarding not permitted for this authentication."); + break; + } + debug("Received TCP/IP port forwarding request."); + channel_input_port_forward_request(pw->pw_uid == 0, options.gateway_ports); + success = 1; + break; + + case SSH_CMSG_MAX_PACKET_SIZE: + if (packet_set_maxsize(packet_get_int()) > 0) + success = 1; + break; + + case SSH_CMSG_EXEC_SHELL: + case SSH_CMSG_EXEC_CMD: + /* Set interactive/non-interactive mode. */ + packet_set_interactive(have_pty || s->display != NULL, + options.keepalives); + + if (type == SSH_CMSG_EXEC_CMD) { + command = packet_get_string(&dlen); + debug("Exec command '%.500s'", command); + packet_integrity_check(plen, 4 + dlen, type); + } else { + command = NULL; + packet_integrity_check(plen, 0, type); + } + if (forced_command != NULL) { + command = forced_command; + debug("Forced command '%.500s'", forced_command); + } + if (have_pty) + do_exec_pty(s, command, pw); + else + do_exec_no_pty(s, command, pw); + + if (command != NULL) + xfree(command); + /* Cleanup user's local Xauthority file. */ + if (xauthfile) + xauthfile_cleanup_proc(NULL); + return; + + default: + /* + * Any unknown messages in this phase are ignored, + * and a failure message is returned. + */ + log("Unknown packet type received after authentication: %d", type); + } + packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); + packet_send(); + packet_write_wait(); + + /* Enable compression now that we have replied if appropriate. */ + if (enable_compression_after_reply) { + enable_compression_after_reply = 0; + packet_start_compression(compression_level); + } + } +} + +/* + * This is called to fork and execute a command when we have no tty. This + * will call do_child from the child, and server_loop from the parent after + * setting up file descriptors and such. + */ +void +do_exec_no_pty(Session *s, const char *command, struct passwd * pw) +{ + int pid; + +#ifdef USE_PIPES + int pin[2], pout[2], perr[2]; + /* Allocate pipes for communicating with the program. */ + if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) + packet_disconnect("Could not create pipes: %.100s", + strerror(errno)); +#else /* USE_PIPES */ + int inout[2], err[2]; + /* Uses socket pairs to communicate with the program. */ + if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || + socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) + packet_disconnect("Could not create socket pairs: %.100s", + strerror(errno)); +#endif /* USE_PIPES */ + if (s == NULL) + fatal("do_exec_no_pty: no session"); + + session_proctitle(s); + + /* Fork the child. */ + if ((pid = fork()) == 0) { + /* Child. Reinitialize the log since the pid has changed. */ + log_init(__progname, options.log_level, options.log_facility, log_stderr); + + /* + * Create a new session and process group since the 4.4BSD + * setlogin() affects the entire process group. + */ + if (setsid() < 0) + error("setsid failed: %.100s", strerror(errno)); + +#ifdef USE_PIPES + /* + * Redirect stdin. We close the parent side of the socket + * pair, and make the child side the standard input. + */ + close(pin[1]); + if (dup2(pin[0], 0) < 0) + perror("dup2 stdin"); + close(pin[0]); + + /* Redirect stdout. */ + close(pout[0]); + if (dup2(pout[1], 1) < 0) + perror("dup2 stdout"); + close(pout[1]); + + /* Redirect stderr. */ + close(perr[0]); + if (dup2(perr[1], 2) < 0) + perror("dup2 stderr"); + close(perr[1]); +#else /* USE_PIPES */ + /* + * Redirect stdin, stdout, and stderr. Stdin and stdout will + * use the same socket, as some programs (particularly rdist) + * seem to depend on it. + */ + close(inout[1]); + close(err[1]); + if (dup2(inout[0], 0) < 0) /* stdin */ + perror("dup2 stdin"); + if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ + perror("dup2 stdout"); + if (dup2(err[0], 2) < 0) /* stderr */ + perror("dup2 stderr"); +#endif /* USE_PIPES */ + + /* Do processing for the child (exec command etc). */ + do_child(command, pw, NULL, s->display, s->auth_proto, s->auth_data, NULL); + /* NOTREACHED */ + } + if (pid < 0) + packet_disconnect("fork failed: %.100s", strerror(errno)); + s->pid = pid; +#ifdef USE_PIPES + /* We are the parent. Close the child sides of the pipes. */ + close(pin[0]); + close(pout[1]); + close(perr[1]); + + if (compat20) { + session_set_fds(s, pin[1], pout[0], s->extended ? perr[0] : -1); + } else { + /* Enter the interactive session. */ + server_loop(pid, pin[1], pout[0], perr[0]); + /* server_loop has closed pin[1], pout[1], and perr[1]. */ + } +#else /* USE_PIPES */ + /* We are the parent. Close the child sides of the socket pairs. */ + close(inout[0]); + close(err[0]); + + /* + * Enter the interactive session. Note: server_loop must be able to + * handle the case that fdin and fdout are the same. + */ + if (compat20) { + session_set_fds(s, inout[1], inout[1], s->extended ? err[1] : -1); + } else { + server_loop(pid, inout[1], inout[1], err[1]); + /* server_loop has closed inout[1] and err[1]. */ + } +#endif /* USE_PIPES */ +} + +/* + * This is called to fork and execute a command when we have a tty. This + * will call do_child from the child, and server_loop from the parent after + * setting up file descriptors, controlling tty, updating wtmp, utmp, + * lastlog, and other such operations. + */ +void +do_exec_pty(Session *s, const char *command, struct passwd * pw) +{ + FILE *f; + char buf[100], *time_string; + char line[256]; + const char *hostname; + int fdout, ptyfd, ttyfd, ptymaster; + int quiet_login; + pid_t pid; + socklen_t fromlen; + struct sockaddr_storage from; + struct stat st; + time_t last_login_time; + + if (s == NULL) + fatal("do_exec_pty: no session"); + ptyfd = s->ptyfd; + ttyfd = s->ttyfd; + + /* Get remote host name. */ + hostname = get_canonical_hostname(); + + /* + * Get the time when the user last logged in. Buf will be set to + * contain the hostname the last login was from. + */ + if (!options.use_login) { + last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name, + buf, sizeof(buf)); + } + + /* Fork the child. */ + if ((pid = fork()) == 0) { + pid = getpid(); + + /* Child. Reinitialize the log because the pid has + changed. */ + log_init(__progname, options.log_level, options.log_facility, log_stderr); + + /* Close the master side of the pseudo tty. */ + close(ptyfd); + + /* Make the pseudo tty our controlling tty. */ + pty_make_controlling_tty(&ttyfd, s->tty); + + /* Redirect stdin from the pseudo tty. */ + if (dup2(ttyfd, fileno(stdin)) < 0) + error("dup2 stdin failed: %.100s", strerror(errno)); + + /* Redirect stdout to the pseudo tty. */ + if (dup2(ttyfd, fileno(stdout)) < 0) + error("dup2 stdin failed: %.100s", strerror(errno)); + + /* Redirect stderr to the pseudo tty. */ + if (dup2(ttyfd, fileno(stderr)) < 0) + error("dup2 stdin failed: %.100s", strerror(errno)); + + /* Close the extra descriptor for the pseudo tty. */ + close(ttyfd); + +/* XXXX ? move to do_child() ??*/ + /* + * Get IP address of client. This is needed because we want + * to record where the user logged in from. If the + * connection is not a socket, let the ip address be 0.0.0.0. + */ + memset(&from, 0, sizeof(from)); + if (packet_connection_is_on_socket()) { + fromlen = sizeof(from); + if (getpeername(packet_get_connection_in(), + (struct sockaddr *) & from, &fromlen) < 0) { + debug("getpeername: %.100s", strerror(errno)); + fatal_cleanup(); + } + } + /* Record that there was a login on that terminal. */ + record_login(pid, s->tty, pw->pw_name, pw->pw_uid, hostname, + (struct sockaddr *)&from); + + /* Check if .hushlogin exists. */ + snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir); + quiet_login = stat(line, &st) >= 0; + + /* + * If the user has logged in before, display the time of last + * login. However, don't display anything extra if a command + * has been specified (so that ssh can be used to execute + * commands on a remote machine without users knowing they + * are going to another machine). Login(1) will do this for + * us as well, so check if login(1) is used + */ + if (command == NULL && last_login_time != 0 && !quiet_login && + !options.use_login) { + /* Convert the date to a string. */ + time_string = ctime(&last_login_time); + /* Remove the trailing newline. */ + if (strchr(time_string, '\n')) + *strchr(time_string, '\n') = 0; + /* Display the last login time. Host if displayed + if known. */ + if (strcmp(buf, "") == 0) + printf("Last login: %s\r\n", time_string); + else + printf("Last login: %s from %s\r\n", time_string, buf); + } + /* + * Print /etc/motd unless a command was specified or printing + * it was disabled in server options or login(1) will be + * used. Note that some machines appear to print it in + * /etc/profile or similar. + */ + if (command == NULL && options.print_motd && !quiet_login && + !options.use_login) { + /* Print /etc/motd if it exists. */ + f = fopen("/etc/motd", "r"); + if (f) { + while (fgets(line, sizeof(line), f)) + fputs(line, stdout); + fclose(f); + } + } + /* Do common processing for the child, such as execing the command. */ + do_child(command, pw, s->term, s->display, s->auth_proto, s->auth_data, s->tty); + /* NOTREACHED */ + } + if (pid < 0) + packet_disconnect("fork failed: %.100s", strerror(errno)); + s->pid = pid; + + /* Parent. Close the slave side of the pseudo tty. */ + close(ttyfd); + + /* + * Create another descriptor of the pty master side for use as the + * standard input. We could use the original descriptor, but this + * simplifies code in server_loop. The descriptor is bidirectional. + */ + fdout = dup(ptyfd); + if (fdout < 0) + packet_disconnect("dup #1 failed: %.100s", strerror(errno)); + + /* we keep a reference to the pty master */ + ptymaster = dup(ptyfd); + if (ptymaster < 0) + packet_disconnect("dup #2 failed: %.100s", strerror(errno)); + s->ptymaster = ptymaster; + + /* Enter interactive session. */ + if (compat20) { + session_set_fds(s, ptyfd, fdout, -1); + } else { + server_loop(pid, ptyfd, fdout, -1); + /* server_loop _has_ closed ptyfd and fdout. */ + session_pty_cleanup(s); + } +} + +/* + * Sets the value of the given variable in the environment. If the variable + * already exists, its value is overriden. + */ +void +child_set_env(char ***envp, unsigned int *envsizep, const char *name, + const char *value) +{ + unsigned int i, namelen; + char **env; + + /* + * Find the slot where the value should be stored. If the variable + * already exists, we reuse the slot; otherwise we append a new slot + * at the end of the array, expanding if necessary. + */ + env = *envp; + namelen = strlen(name); + for (i = 0; env[i]; i++) + if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') + break; + if (env[i]) { + /* Reuse the slot. */ + xfree(env[i]); + } else { + /* New variable. Expand if necessary. */ + if (i >= (*envsizep) - 1) { + (*envsizep) += 50; + env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); + } + /* Need to set the NULL pointer at end of array beyond the new slot. */ + env[i + 1] = NULL; + } + + /* Allocate space and format the variable in the appropriate slot. */ + env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); + snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); +} + +/* + * Reads environment variables from the given file and adds/overrides them + * into the environment. If the file does not exist, this does nothing. + * Otherwise, it must consist of empty lines, comments (line starts with '#') + * and assignments of the form name=value. No other forms are allowed. + */ +void +read_environment_file(char ***env, unsigned int *envsize, + const char *filename) +{ + FILE *f; + char buf[4096]; + char *cp, *value; + + f = fopen(filename, "r"); + if (!f) + return; + + while (fgets(buf, sizeof(buf), f)) { + for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) + ; + if (!*cp || *cp == '#' || *cp == '\n') + continue; + if (strchr(cp, '\n')) + *strchr(cp, '\n') = '\0'; + value = strchr(cp, '='); + if (value == NULL) { + fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf); + continue; + } + /* Replace the equals sign by nul, and advance value to the value string. */ + *value = '\0'; + value++; + child_set_env(env, envsize, cp, value); + } + fclose(f); +} + +/* + * Performs common processing for the child, such as setting up the + * environment, closing extra file descriptors, setting the user and group + * ids, and executing the command or shell. + */ +void +do_child(const char *command, struct passwd * pw, const char *term, + const char *display, const char *auth_proto, + const char *auth_data, const char *ttyname) +{ + const char *shell, *cp = NULL; + char buf[256]; + FILE *f; + unsigned int envsize, i; + char **env; + extern char **environ; + struct stat st; + char *argv[10]; + + f = fopen("/etc/nologin", "r"); + if (f) { + /* /etc/nologin exists. Print its contents and exit. */ + while (fgets(buf, sizeof(buf), f)) + fputs(buf, stderr); + fclose(f); + if (pw->pw_uid != 0) + exit(254); + } + /* Set login name in the kernel. */ + if (setlogin(pw->pw_name) < 0) + error("setlogin failed: %s", strerror(errno)); + + /* Set uid, gid, and groups. */ + /* Login(1) does this as well, and it needs uid 0 for the "-h" + switch, so we let login(1) to this for us. */ + if (!options.use_login) { + if (getuid() == 0 || geteuid() == 0) { + if (setgid(pw->pw_gid) < 0) { + perror("setgid"); + exit(1); + } + /* Initialize the group list. */ + if (initgroups(pw->pw_name, pw->pw_gid) < 0) { + perror("initgroups"); + exit(1); + } + endgrent(); + + /* Permanently switch to the desired uid. */ + permanently_set_uid(pw->pw_uid); + } + if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) + fatal("Failed to set uids to %d.", (int) pw->pw_uid); + } + /* + * Get the shell from the password data. An empty shell field is + * legal, and means /bin/sh. + */ + shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; + +#ifdef AFS + /* Try to get AFS tokens for the local cell. */ + if (k_hasafs()) { + char cell[64]; + + if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) + krb_afslog(cell, 0); + + krb_afslog(0, 0); + } +#endif /* AFS */ + + /* Initialize the environment. */ + envsize = 100; + env = xmalloc(envsize * sizeof(char *)); + env[0] = NULL; + + if (!options.use_login) { + /* Set basic environment. */ + child_set_env(&env, &envsize, "USER", pw->pw_name); + child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); + child_set_env(&env, &envsize, "HOME", pw->pw_dir); + child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); + + snprintf(buf, sizeof buf, "%.200s/%.50s", + _PATH_MAILDIR, pw->pw_name); + child_set_env(&env, &envsize, "MAIL", buf); + + /* Normal systems set SHELL by default. */ + child_set_env(&env, &envsize, "SHELL", shell); + } + if (getenv("TZ")) + child_set_env(&env, &envsize, "TZ", getenv("TZ")); + + /* Set custom environment options from RSA authentication. */ + while (custom_environment) { + struct envstring *ce = custom_environment; + char *s = ce->s; + int i; + for (i = 0; s[i] != '=' && s[i]; i++); + if (s[i] == '=') { + s[i] = 0; + child_set_env(&env, &envsize, s, s + i + 1); + } + custom_environment = ce->next; + xfree(ce->s); + xfree(ce); + } + + snprintf(buf, sizeof buf, "%.50s %d %d", + get_remote_ipaddr(), get_remote_port(), get_local_port()); + child_set_env(&env, &envsize, "SSH_CLIENT", buf); + + if (ttyname) + child_set_env(&env, &envsize, "SSH_TTY", ttyname); + if (term) + child_set_env(&env, &envsize, "TERM", term); + if (display) + child_set_env(&env, &envsize, "DISPLAY", display); + +#ifdef KRB4 + { + extern char *ticket; + + if (ticket) + child_set_env(&env, &envsize, "KRBTKFILE", ticket); + } +#endif /* KRB4 */ + + if (xauthfile) + child_set_env(&env, &envsize, "XAUTHORITY", xauthfile); + if (auth_get_socket_name() != NULL) + child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, + auth_get_socket_name()); + + /* read $HOME/.ssh/environment. */ + if (!options.use_login) { + snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir); + read_environment_file(&env, &envsize, buf); + } + if (debug_flag) { + /* dump the environment */ + fprintf(stderr, "Environment:\n"); + for (i = 0; env[i]; i++) + fprintf(stderr, " %.200s\n", env[i]); + } + /* + * Close the connection descriptors; note that this is the child, and + * the server will still have the socket open, and it is important + * that we do not shutdown it. Note that the descriptors cannot be + * closed before building the environment, as we call + * get_remote_ipaddr there. + */ + if (packet_get_connection_in() == packet_get_connection_out()) + close(packet_get_connection_in()); + else { + close(packet_get_connection_in()); + close(packet_get_connection_out()); + } + /* + * Close all descriptors related to channels. They will still remain + * open in the parent. + */ + /* XXX better use close-on-exec? -markus */ + channel_close_all(); + + /* + * Close any extra file descriptors. Note that there may still be + * descriptors left by system functions. They will be closed later. + */ + endpwent(); + + /* + * Close any extra open file descriptors so that we don\'t have them + * hanging around in clients. Note that we want to do this after + * initgroups, because at least on Solaris 2.3 it leaves file + * descriptors open. + */ + for (i = 3; i < 64; i++) + close(i); + + /* Change current directory to the user\'s home directory. */ + if (chdir(pw->pw_dir) < 0) + fprintf(stderr, "Could not chdir to home directory %s: %s\n", + pw->pw_dir, strerror(errno)); + + /* + * Must take new environment into use so that .ssh/rc, /etc/sshrc and + * xauth are run in the proper environment. + */ + environ = env; + + /* + * Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first + * in this order). + */ + if (!options.use_login) { + if (stat(SSH_USER_RC, &st) >= 0) { + if (debug_flag) + fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC); + + f = popen("/bin/sh " SSH_USER_RC, "w"); + if (f) { + if (auth_proto != NULL && auth_data != NULL) + fprintf(f, "%s %s\n", auth_proto, auth_data); + pclose(f); + } else + fprintf(stderr, "Could not run %s\n", SSH_USER_RC); + } else if (stat(SSH_SYSTEM_RC, &st) >= 0) { + if (debug_flag) + fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC); + + f = popen("/bin/sh " SSH_SYSTEM_RC, "w"); + if (f) { + if (auth_proto != NULL && auth_data != NULL) + fprintf(f, "%s %s\n", auth_proto, auth_data); + pclose(f); + } else + fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC); + } +#ifdef XAUTH_PATH + else { + /* Add authority data to .Xauthority if appropriate. */ + if (auth_proto != NULL && auth_data != NULL) { + if (debug_flag) + fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n", + XAUTH_PATH, display, auth_proto, auth_data); + + f = popen(XAUTH_PATH " -q -", "w"); + if (f) { + fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data); + pclose(f); + } else + fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH); + } + } +#endif /* XAUTH_PATH */ + + /* Get the last component of the shell name. */ + cp = strrchr(shell, '/'); + if (cp) + cp++; + else + cp = shell; + } + /* + * If we have no command, execute the shell. In this case, the shell + * name to be passed in argv[0] is preceded by '-' to indicate that + * this is a login shell. + */ + if (!command) { + if (!options.use_login) { + char buf[256]; + + /* + * Check for mail if we have a tty and it was enabled + * in server options. + */ + if (ttyname && options.check_mail) { + char *mailbox; + struct stat mailstat; + mailbox = getenv("MAIL"); + if (mailbox != NULL) { + if (stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0) + printf("No mail.\n"); + else if (mailstat.st_mtime < mailstat.st_atime) + printf("You have mail.\n"); + else + printf("You have new mail.\n"); + } + } + /* Start the shell. Set initial character to '-'. */ + buf[0] = '-'; + strncpy(buf + 1, cp, sizeof(buf) - 1); + buf[sizeof(buf) - 1] = 0; + + /* Execute the shell. */ + argv[0] = buf; + argv[1] = NULL; + execve(shell, argv, env); + + /* Executing the shell failed. */ + perror(shell); + exit(1); + + } else { + /* Launch login(1). */ + + execl("/usr/bin/login", "login", "-h", get_remote_ipaddr(), + "-p", "-f", "--", pw->pw_name, NULL); + + /* Login couldn't be executed, die. */ + + perror("login"); + exit(1); + } + } + /* + * Execute the command using the user's shell. This uses the -c + * option to execute the command. + */ + argv[0] = (char *) cp; + argv[1] = "-c"; + argv[2] = (char *) command; + argv[3] = NULL; + execve(shell, argv, env); + perror(shell); + exit(1); +} + +Session * +session_new(void) +{ + int i; + static int did_init = 0; + if (!did_init) { + debug("session_new: init"); + for(i = 0; i < MAX_SESSIONS; i++) { + sessions[i].used = 0; + sessions[i].self = i; + } + did_init = 1; + } + for(i = 0; i < MAX_SESSIONS; i++) { + Session *s = &sessions[i]; + if (! s->used) { + s->pid = 0; + s->extended = 0; + s->chanid = -1; + s->ptyfd = -1; + s->ttyfd = -1; + s->term = NULL; + s->pw = NULL; + s->display = NULL; + s->screen = 0; + s->auth_data = NULL; + s->auth_proto = NULL; + s->used = 1; + s->pw = NULL; + debug("session_new: session %d", i); + return s; + } + } + return NULL; +} + +void +session_dump(void) +{ + int i; + for(i = 0; i < MAX_SESSIONS; i++) { + Session *s = &sessions[i]; + debug("dump: used %d session %d %p channel %d pid %d", + s->used, + s->self, + s, + s->chanid, + s->pid); + } +} + +int +session_open(int chanid) +{ + Session *s = session_new(); + debug("session_open: channel %d", chanid); + if (s == NULL) { + error("no more sessions"); + return 0; + } + s->pw = auth_get_user(); + if (s->pw == NULL) + fatal("no user for session %i", s->self); + debug("session_open: session %d: link with channel %d", s->self, chanid); + s->chanid = chanid; + return 1; +} + +Session * +session_by_channel(int id) +{ + int i; + for(i = 0; i < MAX_SESSIONS; i++) { + Session *s = &sessions[i]; + if (s->used && s->chanid == id) { + debug("session_by_channel: session %d channel %d", i, id); + return s; + } + } + debug("session_by_channel: unknown channel %d", id); + session_dump(); + return NULL; +} + +Session * +session_by_pid(pid_t pid) +{ + int i; + debug("session_by_pid: pid %d", pid); + for(i = 0; i < MAX_SESSIONS; i++) { + Session *s = &sessions[i]; + if (s->used && s->pid == pid) + return s; + } + error("session_by_pid: unknown pid %d", pid); + session_dump(); + return NULL; +} + +int +session_window_change_req(Session *s) +{ + s->col = packet_get_int(); + s->row = packet_get_int(); + s->xpixel = packet_get_int(); + s->ypixel = packet_get_int(); + packet_done(); + pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); + return 1; +} + +int +session_pty_req(Session *s) +{ + unsigned int len; + char *term_modes; /* encoded terminal modes */ + + if (s->ttyfd != -1) + return 0; + s->term = packet_get_string(&len); + s->col = packet_get_int(); + s->row = packet_get_int(); + s->xpixel = packet_get_int(); + s->ypixel = packet_get_int(); + term_modes = packet_get_string(&len); + packet_done(); + + if (strcmp(s->term, "") == 0) { + xfree(s->term); + s->term = NULL; + } + /* Allocate a pty and open it. */ + if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) { + xfree(s->term); + s->term = NULL; + s->ptyfd = -1; + s->ttyfd = -1; + error("session_pty_req: session %d alloc failed", s->self); + xfree(term_modes); + return 0; + } + debug("session_pty_req: session %d alloc %s", s->self, s->tty); + /* + * Add a cleanup function to clear the utmp entry and record logout + * time in case we call fatal() (e.g., the connection gets closed). + */ + fatal_add_cleanup(pty_cleanup_proc, (void *)s); + pty_setowner(s->pw, s->tty); + /* Get window size from the packet. */ + pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); + + session_proctitle(s); + + /* XXX parse and set terminal modes */ + xfree(term_modes); + return 1; +} + +int +session_subsystem_req(Session *s) +{ + unsigned int len; + int success = 0; + char *subsys = packet_get_string(&len); + + packet_done(); + log("subsystem request for %s", subsys); + + xfree(subsys); + return success; +} + +int +session_x11_req(Session *s) +{ + if (!options.x11_forwarding) { + debug("X11 forwarding disabled in server configuration file."); + return 0; + } + if (xauthfile != NULL) { + debug("X11 fwd already started."); + return 0; + } + + debug("Received request for X11 forwarding with auth spoofing."); + if (s->display != NULL) + packet_disconnect("Protocol error: X11 display already set."); + + s->single_connection = packet_get_char(); + s->auth_proto = packet_get_string(NULL); + s->auth_data = packet_get_string(NULL); + s->screen = packet_get_int(); + packet_done(); + + s->display = x11_create_display_inet(s->screen, options.x11_display_offset); + if (s->display == NULL) { + xfree(s->auth_proto); + xfree(s->auth_data); + return 0; + } + xauthfile = xmalloc(MAXPATHLEN); + strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); + temporarily_use_uid(s->pw->pw_uid); + if (mkdtemp(xauthfile) == NULL) { + restore_uid(); + error("private X11 dir: mkdtemp %s failed: %s", + xauthfile, strerror(errno)); + xfree(xauthfile); + xauthfile = NULL; + xfree(s->auth_proto); + xfree(s->auth_data); + /* XXXX remove listening channels */ + return 0; + } + strlcat(xauthfile, "/cookies", MAXPATHLEN); + open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600); + restore_uid(); + fatal_add_cleanup(xauthfile_cleanup_proc, s); + return 1; +} + +void +session_input_channel_req(int id, void *arg) +{ + unsigned int len; + int reply; + int success = 0; + char *rtype; + Session *s; + Channel *c; + + rtype = packet_get_string(&len); + reply = packet_get_char(); + + s = session_by_channel(id); + if (s == NULL) + fatal("session_input_channel_req: channel %d: no session", id); + c = channel_lookup(id); + if (c == NULL) + fatal("session_input_channel_req: channel %d: bad channel", id); + + debug("session_input_channel_req: session %d channel %d request %s reply %d", + s->self, id, rtype, reply); + + /* + * a session is in LARVAL state until a shell + * or programm is executed + */ + if (c->type == SSH_CHANNEL_LARVAL) { + if (strcmp(rtype, "shell") == 0) { + packet_done(); + s->extended = 1; + if (s->ttyfd == -1) + do_exec_no_pty(s, NULL, s->pw); + else + do_exec_pty(s, NULL, s->pw); + success = 1; + } else if (strcmp(rtype, "exec") == 0) { + char *command = packet_get_string(&len); + packet_done(); + s->extended = 1; + if (s->ttyfd == -1) + do_exec_no_pty(s, command, s->pw); + else + do_exec_pty(s, command, s->pw); + xfree(command); + success = 1; + } else if (strcmp(rtype, "pty-req") == 0) { + success = session_pty_req(s); + } else if (strcmp(rtype, "x11-req") == 0) { + success = session_x11_req(s); + } else if (strcmp(rtype, "subsystem") == 0) { + success = session_subsystem_req(s); + } + } + if (strcmp(rtype, "window-change") == 0) { + success = session_window_change_req(s); + } + + if (reply) { + packet_start(success ? + SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); + packet_put_int(c->remote_id); + packet_send(); + } + xfree(rtype); +} + +void +session_set_fds(Session *s, int fdin, int fdout, int fderr) +{ + if (!compat20) + fatal("session_set_fds: called for proto != 2.0"); + /* + * now that have a child and a pipe to the child, + * we can activate our channel and register the fd's + */ + if (s->chanid == -1) + fatal("no channel for session %d", s->self); + channel_set_fds(s->chanid, + fdout, fdin, fderr, + fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ); +} + +void +session_pty_cleanup(Session *s) +{ + if (s == NULL || s->ttyfd == -1) + return; + + debug("session_pty_cleanup: session %i release %s", s->self, s->tty); + + /* Cancel the cleanup function. */ + fatal_remove_cleanup(pty_cleanup_proc, (void *)s); + + /* Record that the user has logged out. */ + record_logout(s->pid, s->tty); + + /* Release the pseudo-tty. */ + pty_release(s->tty); + + /* + * Close the server side of the socket pairs. We must do this after + * the pty cleanup, so that another process doesn't get this pty + * while we're still cleaning up. + */ + if (close(s->ptymaster) < 0) + error("close(s->ptymaster): %s", strerror(errno)); +} + +void +session_exit_message(Session *s, int status) +{ + Channel *c; + if (s == NULL) + fatal("session_close: no session"); + c = channel_lookup(s->chanid); + if (c == NULL) + fatal("session_close: session %d: no channel %d", + s->self, s->chanid); + debug("session_exit_message: session %d channel %d pid %d", + s->self, s->chanid, s->pid); + + if (WIFEXITED(status)) { + channel_request_start(s->chanid, + "exit-status", 0); + packet_put_int(WEXITSTATUS(status)); + packet_send(); + } else if (WIFSIGNALED(status)) { + channel_request_start(s->chanid, + "exit-signal", 0); + packet_put_int(WTERMSIG(status)); + packet_put_char(WCOREDUMP(status)); + packet_put_cstring(""); + packet_put_cstring(""); + packet_send(); + } else { + /* Some weird exit cause. Just exit. */ + packet_disconnect("wait returned status %04x.", status); + } + + /* disconnect channel */ + debug("session_exit_message: release channel %d", s->chanid); + channel_cancel_cleanup(s->chanid); + /* + * emulate a write failure with 'chan_write_failed', nobody will be + * interested in data we write. + * Note that we must not call 'chan_read_failed', since there could + * be some more data waiting in the pipe. + */ + if (c->ostate != CHAN_OUTPUT_CLOSED) + chan_write_failed(c); + s->chanid = -1; +} + +void +session_free(Session *s) +{ + debug("session_free: session %d pid %d", s->self, s->pid); + if (s->term) + xfree(s->term); + if (s->display) + xfree(s->display); + if (s->auth_data) + xfree(s->auth_data); + if (s->auth_proto) + xfree(s->auth_proto); + s->used = 0; +} + +void +session_close(Session *s) +{ + session_pty_cleanup(s); + session_free(s); + session_proctitle(s); +} + +void +session_close_by_pid(pid_t pid, int status) +{ + Session *s = session_by_pid(pid); + if (s == NULL) { + debug("session_close_by_pid: no session for pid %d", s->pid); + return; + } + if (s->chanid != -1) + session_exit_message(s, status); + session_close(s); +} + +/* + * this is called when a channel dies before + * the session 'child' itself dies + */ +void +session_close_by_channel(int id, void *arg) +{ + Session *s = session_by_channel(id); + if (s == NULL) { + debug("session_close_by_channel: no session for channel %d", id); + return; + } + /* disconnect channel */ + channel_cancel_cleanup(s->chanid); + s->chanid = -1; + + debug("session_close_by_channel: channel %d kill %d", id, s->pid); + if (s->pid == 0) { + /* close session immediately */ + session_close(s); + } else { + /* notify child, delay session cleanup */ + if (kill(s->pid, (s->ttyfd == -1) ? SIGTERM : SIGHUP) < 0) + error("session_close_by_channel: kill %d: %s", + s->pid, strerror(errno)); + } +} + +char * +session_tty_list(void) +{ + static char buf[1024]; + int i; + buf[0] = '\0'; + for(i = 0; i < MAX_SESSIONS; i++) { + Session *s = &sessions[i]; + if (s->used && s->ttyfd != -1) { + if (buf[0] != '\0') + strlcat(buf, ",", sizeof buf); + strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf); + } + } + if (buf[0] == '\0') + strlcpy(buf, "notty", sizeof buf); + return buf; +} + +void +session_proctitle(Session *s) +{ + if (s->pw == NULL) + error("no user for session %d", s->self); + else + setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); +} + +void +do_authenticated2(void) +{ + /* + * Cancel the alarm we set to limit the time taken for + * authentication. + */ + alarm(0); + server_loop2(); + if (xauthfile) + xauthfile_cleanup_proc(NULL); +} |